Saturday, 12 June 2021


Targets are often presented as though we can choose. In practice there is little choice.  

If we are to avoid being burned to a cinder we have to stop using fossil fuels; to reach ‘net-zero emissions’ we can no longer choose how long to take to reach this target.

The 2015 Paris Agreement set limits to Global Warming that are regarded by the IPCC as consistent with a tolerable existence on planet earth.

 Initially 2°C was set. This limit was modified following an IPCC report (2018) which made clear that a 1.5° increase offered a much better chance of a much better climate.

 With a rise in global temperature of 1°C above pre-industrial temperatures, we are already experiencing extreme weather events: heat-waves and droughts, storms and floods, melting ice and rising sea levels, bleaching of our coral reefs and massive species loss.  Beyond a 1.5°C increase we risk realising our worst nightmare, ‘a cascade of tipping points’ as several natural systems break down. This could happen when the arctic ice is so reduced that instead of reflecting the sun’s rays back into space the radiation is absorbed by the sea, heating the ocean; the global temperature rises melting the permafrost which releases methane, further increasing the greenhouse gases and accelerating the warm-up.

 So! A 1.5°C increase seems to be the least-worst limit on which to agree.

The agreement to limit global temperature increases determines the remaining amount of greenhouse gases we can send into the atmosphere. This in turn translates into a Global Budget of 1,750 Gt CO2 e. There is no choice about this Global Budget, it’s based on science and arithmetic and the need to keep global atmospheric concentrations of CO2 e to 556 parts per million or less.

The Australian Government’s ‘Climate Change Authority’ originally calculated our National ‘fair-share’ budget, taking account of our share of the global population (0.33%) and our contribution to current global emissions (0.97%).

The recently formed independent ‘Climate Target Panel' followed the same methodology to calculate a new Australian ‘fair-share’ budget for 2021 to 2050 as follows: 

- for a 2°C increase the budget is 6,161 mega-tonnes CO2 e (CO2 equivalent) and   

- for a 1.5°C increase it is 3,521 mega-tonnes CO2 e

These figures are based on the science, not the politics, nor the economics nor on any individual’s personal opinion. They stem from the harsh and undeniable reality that if we go on pumping Greenhouse Gases into the atmosphere the world will get unbearably hot.

Back in 2014 it would have been possible to reduce our emissions at a steady (straight-line) amount per year, stretching the budget to reach net-zero emissions by 2050. 

However, since we stopped reducing emissions when the carbon tax was repealed (2016), this is no longer possible; a steady rate of reduction no longer gets us to net-zero by 2050. To avoid over-spending our budget, we now have to reduce emissions more rapidly. According to the Climate Target Panel, at a steady rate of emissions reduction our remaining budget only lasts to 2034.

The conclusion is: ‘time is up’! We no longer have the luxury of choosing how long we have to reach our target of ‘net-zero emissions’. Later than 2050 is too late, and 2050 is not soon enough. What matters if we are to keep our commitment to the Paris Agreement is the Carbon Budget.

         - Nick Reeve